Busting, you sound so good! Your strength is amazing.
With regards to H seeing your mother, I don't really have any great advice, but I will think about it in my own sitch. My mother absolutely adores my W...she always did, even when we weren't together. So if it was the same sitch for me, what would I do?
Honestly, I probably wouldn't want her along because I think it would be uncomfortable. I think that time would be for me and my mother and I wouldn't be able to be myself completely with her there. I would be ok if W continued a relationship with my mom, but it would be on her to do that. I wouldn't help, though I probably would tell her at some point that I was ok with it so that she felt comfortable doing so.